Recently, for example, a liquid crystal display device has been used widely in a liquid crystal television, a monitor, a mobile telephone and the like, as a flat panel display having advantages such as thinness and light-weight in comparison with conventional Braun tubes. Such a liquid crystal display device includes an illumination device (backlight) that emits light and a liquid crystal panel that has a plurality of pixels and displays a desired image by playing a role as a shutter with respect to light from a light source provided in the illumination device.
Further, a liquid crystal display device as described above is a so-called hold-type display device, which holds luminance of each pixel for one frame period (one vertical period) in which one display screen image is rewritten. Because of this, when such a liquid crystal display device displays a moving image, a problem of moving image blurring (pseudo-contour) is caused in some cases, i.e., an outline of a displayed moving object is visually recognized blurringly.
Specifically, in the liquid crystal display device, by applying, on a pixel basis, voltages to a liquid crystal layer contained in the liquid crystal panel in accordance with the gray scale of a display image, an orientation state of liquid crystal molecules and, by extension, a transmittance of each pixel (transmittance of a liquid crystal) are changed for displaying the display image. However, as compared with a so-called impulse-type display device such as CRT, the liquid crystal display device has low responsivity with respect to video data. In other words, the liquid crystal display device generally uses a liquid crystal with a slow response speed (a changing speed of the transmittance of the liquid crystal). Because of this, in the liquid crystal display device, when a gray-scale transition (gray-scale change) occurs between two consecutive frames (display image) at the time of displaying a moving image, an image having a middle gray scale is visually recognized, which sometimes is recognized as the above-described moving image blurring.
Therefore, with respect to a conventional liquid crystal display device, for example, as described in Patent Document 1 below, there has been a proposal of performing an overshoot drive capable of improving the response speed of the liquid crystal. In other words, in this conventional liquid crystal display device, when the gray-scale transition occurs between two consecutive frames, a predetermined gray-scale transition emphasis process (overshoot drive) is performed with respect to video data of the frame in which the gray-scale transition occurs.
Specifically, in this conventional liquid crystal display device, in the two consecutive frames, when the gray-scale transition occurs from a gray scale A to a gray scale B that is higher than the gray scale A for example, a voltage that is higher than a voltage for achieving the gray scale B is applied to the pixel for a predetermined period. Then, a voltage in accordance with the target gray scale B is applied. Consequently, in this conventional liquid crystal display device, it has been considered that the orientation change of liquid crystal molecules is promoted and the response speed of the liquid crystal is improved, whereby the moving image blurring can be suppressed.
Patent Document 1: JP 2001-343956 A